The present invention relates to a method for finishing a manufactured article by powder painting.
Finishing by powder painting is currently widely used in decorating, so as to imitate the grain of a type of wood, metallic profiled elements to be used in particular for door and window parts.
The metallic profiled elements, after being adequately prepared for painting, are subjected to a treatment cycle which provides for the following operating steps: first of all, a first layer of powder paint or primer is deposited on the profiled element; then partial polymerization of the first layer of paint is provided; then a second layer of powder paint, having a different color or shade than the underlying layer, is applied according to a preset graphic configuration; and, final baking is performed to fully polymerize the first and second layers of paint.
The above described painting process, however, has drawbacks which drastically limit the industrial applicability thereof, both in terms of mass-production and of final cost of the finished product. The most critical step of such a treatment cycle is the application of the second layer of paint, i.e., the decorative layer, and this task is often entrusted to the experience and skill of qualified personnel capable of reproducing a particular graphic configuration, such for example an imitation grain, on any metallic or non-metallic substrate, by working manually with the aid of traditional tools such as for example brushes and paintbrushes.
From the above description it is easy to understand that it is not possible to provide an industrial process that includes an operation entirely performed by hand, since this operation constitutes an inevitable and economically unsustainable bottleneck which results in severely slowing the entire production cycle.
Through attempts to convert the process for finishing manufactured articles from a strictly manual to an automated treatment resulted in improvement the speed of the production cycle, they have not been qualitatively successful in terms of resemblance to the original, thus requiring continuous manual intervention by specialized personnel downstream of the treatment cycle.
Examples of powder painting devices are available from the Patent Abstracts of Japan, vol. 008 no. 104 and JP-A-016771 and from U.S. Pat. No. 3,295,440.